As is the case with many joint prostheses or replacements, replicating natural anatomical movement through artificial mechanical devices proves challenging. This is true especially with the knee, which allows for relative complex movement and kinematics between the femoral condyles and the tibia. This relative motion is complex in that it accounts for both rolling and sliding between the contact surfaces at varying rates throughout the flexion arc. Along with such movement during knee bending is a rotational movement between the tibia and femur. As such, knee prostheses have historically tried to replicate the full range of knee movement, throughout and between full flexion and extension in all planes (coronal-varus/valgus, sagittal-flexion, transverse-rotation). True anatomical movement would allow rollback and translation of the femoral condyles on the tibia, all while also allowing rotational movement during flexion/extension.
Prior art designs have included femoral components with cams and tibial components with posts. It has been disclosed that an asymmetrical cam can be utilized to cause rotation between the two components. These designs, however, have taught architectures that require relatively high posts to support upward movement of the cam during flexion and/or rely on the anterior-posterior position of the post and cam. Other prior art designs have disclosed the use of tibial bearing surfaces to cause rotation between the components. These designs, however, have taught architectures that require tibial components that are asymmetrical in the lateral-medial cross-section.